MongoDB Query Collation

• Query all
  Sql:select * FROM table_name
  Mongodb:db.getCollection (' Journal paper '). Find ({})
  

  As shown, get all the data under the journal paper Collection

• Conditional query
  Note: Please note that the data type of the selected column
  1. Journal _title = ' Nature '
  Sql:select * FROM table_name where journal_title = ' Nature '
  Mongodb:db.getCollection (' Journal paper '). Find ({"Journal_title": "Nature"})
  

  2. volume<495:
  Sql:select * FROM table_name where volume< 495;
  Mongodb:db.getCollection (' Journal paper '). Find ({"Volume": { $lt:"495"}). Pretty ()
  

  3. Volume <= 495
  Sql:select * FROM table_name where volume<= 495;
  Mongodb:db.getCollection (' Journal paper '). Find ({"volume": { $lte : " 495 "}}). Pretty ()
  
  4. Volume >495
  Sql:select * FROM table_name where volume> 495;
  Mongodb:db.getCollection (' Journal paper '). Find ({"volume": { $gt : "495 "}}). Pretty ()
  
  5. Volume!=495
  Sql:select * FROM table_name where volume! = 495;
  Mongodb:db.getCollection (' Journal paper '). Find ({"volume": { $ne : "495"}} ). Pretty () and, or query

6. And query:
Sql:select * FROM table_name where journal_title = ' Nature ' and vulome> 495;
Mongodb:db.getCollection (' Journal paper '). Find ({"Journal_title": "Nature" Volume: { $gt : "495"}}). Pretty ()

7. or query:
Sql:select * FROM table_name where journal_title = ' Nature ' or vulome> 495;
Mongodb:db.getCollection (' Journal paper '). Find ({$or: [{"Journal_title": "Nature"} ,{ "volume": { $GT : "495"}]}). Pretty ()

8. And and or union query:
Sql:select * FROM table_name where volume>52 and Journ Al_title = ' Nature ' or journal_title = ' Meccanica ';
Mongodb:db.getCollection (' Journal paper '). Find ({"volume": {$gt: ' '}, $or: [{"Journal_title": "Nature"},{"Journal_title ":" Meccanica "}]}). Pretty ()

• Get the number of data
  Sql:select Count (*) from table_name
  Mongodb:db.getCollection (' Journal paper '). COUNT ()
  

• Group queries
  Sql:select Journal_title, COUNT (*) from table_name GROUP BY Journal_title
  Mongodb:db.getCollection (' Journal paper '). Aggregate ([{$group: {_id: "$journal _title", num_tutorial: {$sum: 1}}])
  
  
  
• Sort
  Using the sort () method to sort data in MongoDB, the sort () method can specify a sorted field by parameter and use 1 and-one to specify how the sort is sorted, where 1 is in ascending order, and 1 is used for descending order
  
  

MongoDB Query Collation